A new empirical formula for α-decay half-life and decay chains of Z=120 isotopes

Experimental alpha-decay half-life, spin, and parity of 398 nuclei in the range 50 <= Z <= 118 are utilized to propose a new formula (QF) with only 4 coefficients as well as to modify the Tagepera-Nurmia formula with just 3 coefficients (MTNF) by employing nonlinear regressions. These formulas, based on reduced mass (mu) and angular momentum taken away by the alpha-particle, are ascertained very effective for both favoured and unfavoured alpha-decay in addition to their excellent match with all (Z, N) combinations of experimental alpha-decay half-lives. After comparing with similar other empirical formulas of alpha-decay half-life, QF and MTNF formulas are purported with accuracy, minimum uncertainty and deviation, dependency on least number of fitted coefficients together with less sensitivity to the uncertainties of Q-values. The QF formula is applied to predict alpha-decay half-lives for 724 favoured and 635 unfavoured transitions having experimentally known Q-values. Moreover, these available Q-values are also employed to test various theoretical approaches viz. RMF, FRDM, WS4, RCHB, etc along with machine learning method XGBoost for determining theoretical Q-values, incisively. Thereafter, using Q-values from the most precise theoretical treatment mentioned above along with the proposed formulas, probable alpha-decay chains for Z = 120 isotopes are identified.